Rotary and hammer drill



Jan. 16,1968 F. c. BOGUSCH, JR 3,363,700

ROTARY AND HAMMER DRILL Filed Aug. 24, 1965 2 Sheets-Sheet l INVENTOR.

' FRANK 0. soausau, JR. F/GJ BY QM wT-vuw:

ATTORNEY Jan. 16, 1968 c, BOGUSCH, JR 3,363,700

ROTARY AND HAMMER DRILL Filed Aug. 24, 1965 2 Sheets-Sheet 2 INVENTOR FRANK 6. BOGUSCH, JR.

ATTORNEY Q wToLLw:

United States Patent Ofiice ABSTRACT OF THE DISCLOSURE A power hammer that simultaneously impacts and to tates a bit and including an electric motor rotating a slid ably mounted anvil riding against a hammer fixed in the tool casing. The anvil and hammer include cooperating cam surfaces which periodically engage to deliver a series of axial impacts to the tool bit as it rotates.

This invention relates to a combination rotary and hammer drill driven by a rotary motor and generally having the characteristics of a portable hand-held power tool.

The principal object of this invention is to provide a combination rotary and hammer drill which is relatively economical, reliable, long lasting and of a compact size.

Other important objects of this invention are: to provide a combination rotary and hammer drill mechanism driven by a rotary motor having a cam mechanism with good wearing qualities; to provide a combination rotary and hammer drill mechanism having a cam mechanism containing rotary elements which are protected from damage by the impact forces created in the mechanism; to provide a combination rotary and hammer drill mechanism in which the impact force loads are relatively distributed to reduce impact load wear on the mechanism; and to provide a combination rotary and hammer drill mechanism of the axial cam type having a relatively small diameter.

In brief, the foregoing objects are attained in a combination rotary and hammer drill utilizing an axial cam mechanism formed of a pair of interengaging conical cam surfaces and providing a rolling means on one cam surface and a cam means on the other cam surface for engaging the rolling means to thrust the two cam surfaces apart and by providing the cam means with-a greater height than the rolling means to prevent the rolling means from engaging the opposite cam surface during impact, thus protecting the rolling means from transmitting impact loads. This expedient protects the rolling means from wear caused by the transfer of impact loads.

The invention is described in connection with the ac companying drawings wherein:

FIG. 1 is a fragmentary elevational view with portions cut away of the nose or front end of a combination rotary and hammer drill embodying the present invention;

FIG. 2 is a section taken on line 22 of FIG. 1;

FIG. 3 is a section taken on line 3-3 of FIG. 1;

FIG. 4 is a section taken on line 4-4 of FIG. 1;

FIG. 5 is a section taken on line 55 of FIG. 1;

FIG. 6 is a section similar to FIG. 5 and showing the cam surfaces immediately after impact and while the cam lobes on one surface are disengaged from the rolling means on the other cam surface and are riding on the portions of the cam surface intermediate the rolling means;

FIG. 7 is a fragmentary diagrammatic view illustrating a cross section of the conical cam surfaces lying in a plane and showing the position of the cam surfaces immediately prior to engagement between the cam lobes and the rolling means;

FIG. 8 is similar to FIG. 7 and shows the cam lobes engaging the rolling means to thrust the hammer away from the anvil;

FIG. 9 is similar to FIGS. 7 and 8 and shows the cam lobes disengaged from the rolling means and impacting with the hammer; and

FIG. 10 is a fragmentary section illustrating an alternative embodiment of impact mechanism.

The combination rotary hammer drill 1 is shown fragmentarily in FIG. 1 and includes a casing 2 containing a nose or front end 3. The drill 1 contains a motor (not a drive shaft 4 mounted in bearings 5 disposed in the rear of the nose 3. A spindle 6 carries a suitable chuck 7 and is mounted in a sleeve bearing 8 provided in the front end of the nose 3. The spindle 6 is located forward of and in axial alignment with the drive shaft 4. As shown in the drawing, the nose 3 of the casing 2 can be formed of several parts attached together by means such as the threaded portions shown in FIG. 1. The chuck 7 i arranged to hold a suitable hit (not shown) which can be either a rotary drill bit or a hammer drill bit, such as will be used in drilling masonry.

The rear end of the spindle 6 is provided with an en larged shoulder 11 and a reduced diameter stem 12 projecting rearwardly from the shoulder 11. An anvil 13 having an internal axial bore 14 is press-fitted on the reduced stem 12 of the spindle 6 to seat against the rear face of the shoulder 11 in a manner rigidly attaching the anvil 13 to the spindle 6 so that both rotate and move axially as an integral member.

The forward end of the drive shaft 4 is provided with splines 15 which project into the axial bore 14 of the anvil 13 at its rear end and slida'bly engage cooperating splines provided in the rear end of the bore 14, thus causing the drive shaft 4 to have a rotary driving engagement with the anvil 13. A spring 17 is located between the rear end of the spindle 6 and the front end of the drive shaft 4 and seats in a pocket 18 provided in the rear end of the spindle 6. The spring 17 provides a relatively small biasing force constantly urging the spindle 6 axially forward away from the drive shaft 4. The spring 17 can be easily overcome during operation of the tool by the operator pressing the tool axially forward against the work.

The rear end of the anvil 13 is formed as a conical cam surface 19 which diverges forwardly and outwardly relative to the tool as shown in FIG. 1. Generally, the surface of the conical cam surface 19 is located at about 45 to the axis of the spindle 6 and drive shaft 4. A fixed hammer 20 is fixed in the casing nose 3 immediately to the rear of the conical cam surface 19 on the anvil 13. The hammer 20 contains a conical cam surface 21 facing forward and shaped to conform substantially with the conical cam surface 19 on the rear end of the anvil 13. The hammer 20 is termed a hammer because, as will be seen in the description of the operation of the tool, it reciprocates axially with the tool casing 2 during tool operation and delivers a percussive impact to the anvil 13 which in turn transmits such impact to the drill bit (not shown) mounted in the chuck 7.

The conical cam surface 21 on the hammer 2t] contains several angularly spaced rollers 22 located on its face and rotatively mounted in roller pockets 23, which hold the rollers 22 loosely enough to permit free rotation. The major portion of each roller 22 is disposed in its pocket 23 while a minor portion of the periphery of the roller 22 extends from the pocket 23 above the conical cam surface 21. Thus, the rollers 22 are free to rotate while they are locked within their pockets 23. In other words, the walls of each pocket 23 extend around its roller 22 substantially beyond its diametrical center to hold the roller 22 within the pocket. The rollers 22 are inserted axially into the hammer pockets 23 prior to assembly of the casing nose 3.

The conical cam surface 19 on the anvil 13 is provided with several cam lobes 25 which extend above the surrounding cam surface 19 and are adapted to engage the rollers 22 on the hammer cam surface 21. The number of cam lobes 25, four are shown in the drawings, is the same as the number of rollers 22 on the hammer cam surface 21, and the cam lobes 25 are angularly spaced so that each cam lobes 25 will engage a corresponding roller 22 simultaneously during the operation of the tool.

Each cam lobe 25 is provided with a front-lifting ramp 26 which is located in a plane extending at an angle to the axis intermediate a radial plane and a tangential plane so that the cam lobe 25 will lift the hammer during engagement with a cam roller 22 in a smooth motion, which is substantially less than an abrupt motion, thus eliminating a percussive or impact axial motion. The rear ramp 27 on each cam lobe lies substantially in a radial plane so that the cam lobe 25 will provide a substantially abrupt disengagement between the cam lobe 25 and a roller 22 as the cam lobe rotates by a roller. Abrupt disengagement between a cam lobe 25 and a corresponding roller 22 is required to provide the necessary impact action of the hammer mechanism.

The height of each cam lobe 25 above its surrounding anvil cam surface 19 is substantially greater than the height of each roller 22 above its surrounding hammer cam surface 21 so that the rollers 22 do not engage the anvil cam surface 19 when the cam lobes 25 are disengaged from the rollers 22. This arrangement ensures that the rollers 22 on the hammer cam surface 21 do not transmit or provide an impact force to the anvil 13 as the cam lobes 25 drop off of the rollers 22. It is believed to be obvious at this time that the impact force is created after the cam lobes 25 engage corresponding rollers 22 to force the cam surfaces 19 and 21 apart and then drop otf of the rollers 22 so that the cam lobes 25 re-engage the surrounding hammer cam surface 21 thus creating an impact.

Means is shown in FIG. 1, for selectively limiting the drill to a rotary drilling motion, without impact, when desired. A thrust bearing 29 is mounted on the spindle 6 immediately forward of the anvil 13 and is held in place against the front end of the anvil 13 by a lock ring 30 engaged around the spindle 6. A control ring 31 is disposed within the casing nose 3 surrounding the anvil 13. It is carried by radial pins 32 extending radially outward through the casing nose 3 and fixed in a control sleeve 33 surrounding the casing nose 3. The control ring 31 is adapted to engage the bearing 29 and prevent the spindle 6 and anvil 13 from moving rearwardly sufiiciently to provide an impact between the anvil 13 and the hammer 20.

Arranging the impact mechanism so that the rollers 22 do not transmit impact forces protects the rollers 22 from rapid wear. As a result, the impact mechanism has good wearing characteristics.

Providing the anvil 13 and hammer 20 with the conical cam surfaces 19 and 21 enables the reduction of the diameter of the impact mechanism. In addition, the height of the rollers 22 above the pockets 23 can be less for a given hammer travel as compared to an impact mechanism having engaging surfaces located at right angles to the axis of the mechanism.

The control ring 31 can be moved sufficiently rearward to allow the anvil 13 to impact with the hammer 20 by rotating the control sleeve 33. The pins 32 are located in L-shaped cam slots 34 provided in the casing nose 3, as shown in FIG. 4. The L-shaped slots 34 include a short leg 35 and a long leg 36. The movement of the pins 32 into alternate legs 35 and 36 provides the alternate type of drilling operation, either pure rotary drilling or combined rotary and hammer drilling.

When the pins 32 are disposed in the short legs 35 of the L-shaped slots 34, the control ring 31 is located sufficiently forward to prevent the anvil 13 from engaging the hammer 20. Alternately, when the pins 32 are disposed in the long legs 36 of the slots 34, the control ring 31 is moved sufficiently rearward to allow the anvil 13 to engage and impact with the hammer 20. The pins 32 are located in the alternate legs 35 or 36 merely by turning the control sleeve 33. A spring 38 is located between the interior of the front end of the nose 3 and the control ring 31 to constantly urge the control ring 31 rearwardly thus to hold the radial pins 32 in the ends of either legs 35 or 36 of the L-shaped slots 34.

Operation At the start of operation, we assume that the control sleeve 33 is rotated to dispose the pins 32 in the long legs 36 of the slots 34 so as to move the control ring 31 rearward to allow percussive impact between the anvil 13 and the hammer 20. The motor of the tool 1 is rotating the drive shaft 4, as a result, transmitting rotary motion through the anvil 13 to the spindle 6 and driving the chuck 7 which, it is assumed, holds a suitable percussion drill bit. The operator presses downwardly on the tool 1 to force the bit against a work surface and, as a result, compresses the spring 17 to force the anvil 13 against the hammer 20. As the cam lobes 25 on the anvil 13 rotate, the front ramps 26 of each lobe 25 will engage and ride up on a corresponding roller 22 resulting in thrusting the hammer 20 and the tool casing 2 away from the anvil 13. This action is shown in FIGS. 7 and 8. Immediately thereafter, the cam lobe 25 will rotate past the roller 22 and drop off of it abruptly, as shown in FIG. 9, thus allowing the thrusting force applied to the drill by the operator to cause the hammer 20 to move forward against the anvil 13 with an impacting engagement. The impact engagement takes place between the cam lobes 25 and the conical hammer cam surface 21, without the rollers 22 engaging the anvil 13, thus preventing any impact force being transmitted through the rollers 22. The foregoing operation will take place periodically to apply a series of axial impacts to the drill bit held in the chuck 7. Hence, the tool applies a combination rotary and axial hammering motion to the drill bit.

In the case where it is desired to eliminate the axial hammering motion of the tool, the control sleeve 33 is rotated to locate the radial pins 32 in the short legs 35 of the slots 34, thus locating the control ring 31 in a forward position where it engages the bearings 29 and holds the spindle 6 in a forward position where the anvil 13 cannot engage the hammer 20. In this position the drive shaft 4 simply turns the anvil 13 and spindle 6.

FIG. 10 illustrates a second embodiment of the tool wherein the rollers 22 are replaced with a pair of ball bearings 40 which serve as the rolling means for thrusting the anvil 13 forward each time the cam lobe 25 of the anvil engages a corresponding pair of ball bearings 40. Otherwise than for the substitution of the bearings 40 for the rollers 22, the drill shown in FIG. 10 is identical to the drill of FIG. 1.

Although a number of embodiments of the invention are illustrated and described in detail, it will be understood that the invention is not limited simply to the described embodiments, but contemplates other embodiments and variations which are obvious from an understanding of the described embodiments and are embraced within the claims of the invention.

Having described my invention, I claim:

1. A drilling tool comprising:

a frame;

a rotary shaft mounted on said frame;

a spindle mounted on said frame in axial alignment with said shaft for rotary and axial movement and having means for carrying a drill bit;

means interconnecting said shaft and spindle for transmitting torque therebetween and allowing said pindle to move axially relative to said shaft;

an anvil carried by said spindle to rotate with it and having a conical cam surface;

a hammer mounted on said frame rearwardly of said anvil and having a conical cam surface for engaging the conical cam surface on said anvil;

sai-d conical cam surfaces extending at substantially 45 degree angles to the axes of said shaft and spindle;

rolling means including an elongated roller mounted on one of said conical cam surfaces; and

cam means including an elongated cam mounted on the other of said conical cam surfaces for periodically engaging said elongated roller to force said two cam surfaces apart and to periodically drive said drill bit forwardly;

said elongated cam being located to simultaneously engage said elongated roller along substantially the full length of said roller.

2. The tool of claim 1 wherein:

the height of said elongated roller above its conical cam surface is less than the height of said elongated 20 cam above its conical cam surface so that said rolling means is free of engagement between said cam surfaces after said cam means moves off of said roller means.

3. The tool of claim 1 wherein:

said rolling means is mounted on the cam surface of said hammer.

4. The tool of claim 1 including:

selective means for holding said hammer and anvil axially apart to prevent the drill from producing axial impacts.

References Cited UNITED STATES PATENTS 1,044,790 11/1912 Lange 173109 X 2,869,374 1/1959 Morris 74-22 2,942,852 6/1960 Muthmann 173-109 2,974,533 3/1961 Demo 173-123 X 3,119,274 1/1964 Short 17448 X 3,163,237 12/1964 Fulop 173-109 FRED C. MATTERN, JR., Primary Examiner. L. P. KESSLER, Assistant Examiner. 

